The present invention relates to an operation unit provided with an operation member including an outer surface having a parting line.
A typical vehicle includes electrical devices such as an air conditioner and audio equipment. An operation unit, which is arranged in the passenger compartment, is operated to control such a device. Japanese Laid-Open Patent Publication No. 2010-122992 describes an example of such an operation unit.
The operation unit of Japanese Laid-Open Patent Publication No. 2010-122992 includes a case and an operation member, which is held in a state slidable and movable relative to the case. Referring to FIG. 8, a cylindrical operation member 80 includes a slide portion 81, a step portion 82, and a knob 83. The slide portion 81 is movable relative to the case. The step portion 82 is continuous with an upper part of the slide portion 81 and has a smaller diameter than the slide portion 81. The knob 83 is continuous with an upper part of the step portion 82 and has a smaller diameter than the step portion 82. Knurls 84 are formed on the outer surface of the knob 83 to prevent slipping. Each knurl 84 is pyramidal. A lubricant such as grease is applied to the outer surface of the slide portion 81 to reduce friction between the slide portion 81 and the case. This allows for smooth rotation of the operation member 80 relative to the case.
The operation member 80 of Japanese Laid-Open Patent Publication No. 2010-122992 is injection molded. Injection molding is performed by filling a plurality of molds with thermoplastic resin. This allows for easy molding of a product having a complicated shape. However, an elevated line referred to as a parting line is formed on a molded product at where molds meet. Four parting lines PL are formed on the outer surface of the operation member 80. The four parting lines PL are formed at equal intervals in the circumferential direction. Each parting line PL extends straight from the slide portion 81 to the knob 83.
The lubricant applied to the slide portion 81 may be transferred to the knob 83 along the parting lines PL due to capillary action. When the lubricant is transferred to the knob 83, the lubricant may stick to a user's hand as the user operates the knob 83.
To solve this problem, a through hole 85 extending through the operation member 80 from its outer surface to its inner surface is arranged on each of the four parting lines PL between the knurls 84 and the slide portion 81. The through holes 85 block the capillary action of the lubricant along the parting lines PL.
Such an operation unit often includes a light source arranged in the operation member 80. This forms a path of light in the operation member 80 and illuminates a panel (not shown), which is arranged in the vicinity of the distal end of the operation member 80, from the rear. The light leaking through the panel allows the user to recognize the operation positions or the like of the operation member 80 especially in the nighttime. However, when the light source is arranged in the operation member 80, the light emitted from the light source may also leak from the through holes 85. The leaked light will illuminate the surrounding of the operation member. This is not preferable from an aesthetic viewpoint. Japanese Laid-Open Patent Publication No. 2010-122992 illustrates that the through holes 85 may be replaced by openings or recesses that do not extend through the wall of the operation member 80. However, in this case, each parting line PL remains connected and is not split apart. That is, the capillary action of the lubricant that occurs along the parting line PL is not blocked. Thus, there is a demand for development of an operation unit that suppresses the occurrence of a capillary action without the through holes 85 and prevents lubricant from leaking to the exterior.